Floor grinders: width, grinding pressure and power supply

The order is not random — the width determines how quickly you cover the surface, the grinding pressure determines what you actually get done, and the power supply determines which of the machines you can use at all.

The Husqvarna PG series ranges from 280 to 820 mm grinding width. The weight follows suit: from 72 kg on the PG 280 to 455 kg on the PG 820.

The machines, by width

• PG 280 — 280 mm, 72 kg, 2.2 kW, 1-phase 230 V, one grinding disc at 1 410 rpm
• PG 400 — 400 mm, 110 kg, 4 kW, 3-phase 400 V, one grinding disc at 1 450 rpm
• PG 450 — 450 mm, 109 kg, 2.2 kW, 1-phase 230 V, three grinding discs at 705 rpm
• PG 530 — 530 mm, 210 kg and 4.75 kW on 3-phase or 200 kg and 3.75 kW on 1-phase, speed 200–950 rpm on 3-phase and 200–900 rpm on 1-phase
• PG 680 — 680 mm, 400 kg, 12.5 kW, 3-phase 400 V, 300–1 200 rpm
• PG 820 — 820 mm, 455 kg, 12.5 kW, 3-phase 400 V, 250–1 100 rpm

Grinding pressure is what does the grinding

The diamond only cuts when it is pressed down. The operator's manual for the PG 680 and PG 820 lists pressure among the factors that affect how quickly the diamond segments wear, and as a general rule, the faster they wear, the faster the work goes. The specified max. grinding pressure ranges from 27 kg on the PG 280 to 290 kg on the PG 820.

Note the PG 400 and PG 450: the PG 400 is the heavier of the two (110 vs 109 kg), but the PG 450 has the higher grinding pressure (59 vs 49 kg). Grinding pressure depends on how the weight of the chassis is distributed, and on both machines it can be increased or reduced by changing the angle of the frame. So weight alone does not tell you how hard the machine grinds.

One disc or three

The PG 280 and PG 400 have a single disc that runs fast — around 1 400 rpm. The PG 450, 530, 680 and 820 have three discs on a planetary head, and they run more slowly: 705 rpm on the PG 450, and adjustable from 200 to 1 200 rpm on the larger ones.

The largest also have independent direction control of both the grinding discs and the planetary head, so that each can be run forwards or in reverse separately. The PG 530 runs both ways, but its discs and planetary head rotate in the same direction.

The power supply on site sets the limit

This is worth checking before the machine is ordered, not when it is already on site.

• 1-phase 230 V: PG 280 at 13.4 A and PG 450 at 13 A
• 3-phase 400 V: PG 400 at 7.31 A, PG 680 at 27 A, PG 820 at 27 A
• Both: PG 530, 16 A on 3-phase and 14 A on 1-phase

Remote-controlled versions

The PG 680 and PG 820 are also available as RC, i.e. remote-controlled. They have 13 kW compared with 12.5, and the built-in battery, which makes the machine easy to move to and from the work site, is typically charged in two hours from 1- or 3-phase. One thing to note: the PG 820 RC is specified with 301 kg total grinding pressure (330 kg with support wheel) compared with 290 kg on the hand-guided PG 820. So remote control does not cost you pressure.

The dust extractor is not an accessory

The product pages and the dust extractors' data sheets state which dust extractor goes with each grinder, and it is matched to the machine. The PG 280 has the DC 1400 as its recommended dust extractor, the PG 450 has the DC 3000, and everything from the PG 530 3-phase upwards is listed with the DC 6000. Factor it into both the budget and the power supply plan.